Coated abrasive containing epoxy binder and method of producing the same

Abstract

The use of an aromatic amine salt of a substituted pentafluoroantimonic acid as a curing agent for epoxy resins, and the use of the epoxy resin compositions as binders for abrasives in abrasive sheet products, are disclosed. The aromatic amines are selected from aniline and hindered aromatic amines.

We claim: 
     
       1. In a coated abrasive product including abrasive granules which are supported on and adherently bonded to at least one major surface of a backing sheet by a make coating of a first resinous binder material and a size coating of a second resinous binder material, the improvement comprising at least one of the said resinous materials being epoxy resin, said epoxy resin characterized by comprising cured epoxy resin and residual curing agent derived from substituted pentafluoroantimonic acid and an aromatic amine selected from the group consisting of aniline and hindered amine. 
     
     
       2. The abrasive product of claim 1 wherein said backing sheet is formed of paper, film, fiber, or woven cloth. 
     
     
       3. The abrasive product of claim 1 wherein said abrasive granules are selected from the group consisting of flint, garnet, aluminum oxide, alumina:zirconia, diamond, and silicon carbide. 
     
     
       4. In a coated abrasive product including abrasive granules which are supported on and adherently bonded to at least one major surface of a backing sheet by a resinous binder material, the improvement comprising epoxy resin as the resinous binder material, said epoxy resin being characterized by comprising cured epoxy resin and residual curing agent derived from substituted pentafluoroantimonic acid and an aromatic amine selected from the group consisting of aniline and hindered amine. 
     
     
       5. In a method of making coated abrasive products having the steps of (1) uniformly coating a backing sheet with a make coat of a first resinous material in liquid form;   (2) depositing a plurality of abrasive granules uniformly over the surface of said make coat of first resinous material;   (3) curing said first resinous material to adherently bond said granules to said backing sheet surface;   (4) coating over said make coat and said granules with a size coat of a second resinous material; and   (5) curing the resultant coated product until said second resinous material is solid, the improvement comprising employing, as at least one of said first or said second resinous binder materials, a latent room-temperature stable, curable system comprised of (A) epoxy resin composition having a 1,2-epoxy equivalency greater than one; and   (B) a curing agent in an amount sufficient to cure said composition on heating comprising (1) substituted pentafluoroantimonic acid having the general formula H +  SbF 5  X -  wherein X is halogen, a hydroxy, or an OR group wherein OR is the residue of an aliphatic or aromatic alcohol; and   (2) an aromatic amine selected from the group consisting of aniline; and hindered amine the mole ratio of said substituted pentafluoroantimonic acid to aromatic amine being in the range of 1:05 to 1:4.       
     
     
       6. The method of claim 5 wherein said hindered amine has the general formula ##STR5## wherein: R 1  and R 2  are independently hydrogen, primary or secondary lower alkyl group having 1-6 carbon atoms, or benzyl; R 3 , R 4 , and R 5  are independently hydrogen, an electron donating group, benzyl, or at least one of R 3  and R 4  is joined together with R 5  to form a benzo group; provided that,   if no benzo group is present in said hindered amine, at least one of R 1 , R 2 , R 3 , and R 4  is an alkyl group or an electron donating group; and   if R 3 , R 4  and one of R 1  or R 2  is hydrogen, the other R 1  or R 2  is an alkyl group having at least 2 carbon atoms.   
     
     
       7. The method of claim 5 wherein said OR group is 2-(2-hydroxyethoxy)ethoxy. 
     
     
       8. The method of claim 5 wherein said OR group is the residue of an aliphatic alcohol having a molecular weight of at least 32 and a primary or secondary hydroxyl functionality of at least 1. 
     
     
       9. The method of claim 5 wherein said alcohol is selected from the group consisting of ethylene glycol, diethylene glycol and triethylene glycol. 
     
     
       10. The method of claim 5 wherein said hindered amine is selected from the group consisting of N-methyl-2,6-diethylaniline, 2,6-dimethylaniline, 2,6-diethylaniline, N-sec butylaniline, N,N-diethyl-2,5-dimethyl aniline and N,N-diethyl-2-methylaniline. 
     
     
       11. The method of claim 5 wherein said A also includes up to one hydroxyl equivalent per epoxy equivalent of an alcohol having a functionality of at least one. 
     
     
       12. The method of claim 5 wherein said A also includes coreactive cationically polymerizable ethylenically unsaturated monomer. 
     
     
       13. The method of claim 12 wherein said cationically polymerizable ethylenically unsaturated monomer is selected from the group consisting of styrene, t-butyl styrene, dipentene, and indene. 
     
     
       14. The method of claim 5 wherein said curing agent is contained in a concentration which results in a concentration of 2 to 500 millimoles of antimony per kilogram total weight of curable composition.